#supernatant{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 999;
    background: rgba(0,0,0,0.8);
    >div:nth-child(1){
        width: 100%;
        height: 46px;
        border: 2px dashed #ffffff;
        text-align: center;
        color: #FFFFFF;
        line-height: 46px;
    }
    >div:nth-child(2){
        width: 0px;
        height: 0px;
        margin: 0 auto;
        border: 20px solid rgba(0,0,0,0);
        border-bottom-color:#FFFFFF ;
    }
    >div:nth-child(3){
        width: 20px;
        height: 30px;
        margin: 0 auto;
        border-left: 14px solid #ffffff;
        border-bottom: 0px solid #FFFFFF;
        border-radius: 0 0 0 30px;
        position: relative;
        left: 10px;
    }
}
header{
    width: 100%;
    height: 50px;
    background: rgba(255,255,255,0.8);
    padding: 0 20px;
    box-sizing: border-box;
    line-height: 50px;
    position: fixed;
    top: -50px;
    left: 0;
    transition: top 0.5s ease;
    z-index: 2;
    >p{
        float: left;
        font-size: 18px;
        font-weight: bold;
        small{
            font-size: 16px;
            margin-left: 10px;
            color: #999999;
        }
    }
    >ul{
        float: right;
        display: flex;
        list-style: none;
        a{
            padding: 5px 26px;
            text-decoration: none;
            color: #000000;
            border-radius: 4px;
        }
        a:hover{
            background: rgba(179,179,179,1);
        }
    }
}
section{
    width: 100%;
    height: 100vh;
    overflow: hidden;
}
#home{
    background: green;
 
}
#intro{
    background: blue;
    
}
#skill{
    background: yellow;
}
#undergo{
    background: goldenrod;
}
